JP2010237099A - Method and system for noise evaluation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately obtain results of noise evaluation with high spatial resolution in a short time, regardless of the type of the frequency of noise to be injected. <P>SOLUTION: A noise signal generated by a signal generator 12 is applied directly to a connector 16 of an object to be evaluated 11 via an amplifier 13; a directional coupler 14; and a bias tee 15. Noise which occurs from the object to be evaluated 11 is detected to measure its intensity as sequentially moving a probe 17 over a plurality of measuring points. At this time, a PC 23 controls a spectrum analyzer 21 and a signal generator 12 to sweep measurement frequencies of the spectrum analyzer 21 and synchronize the frequency of a noise signal generated by the signal generator 12 with its sweep frequency. It is thereby possible to obtain measurement data with respect to all the plurality of types of measuring frequencies a single measurement point. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a noise evaluation method and a noise evaluation system for evaluating noise generated from an evaluation object with respect to noise applied to the evaluation object from outside.

  In recent years, advanced functionality has been advanced in all electronic devices such as home appliances / information terminals and electronic control devices for automobiles. On the printed circuit boards that make up electronic devices, the mounting density of various electronic components such as LSIs has increased. Increasing complexity and speeding up / miniaturization of LSIs are progressing. Therefore, when designing electronic equipment, electromagnetic compatibility (EMC) such as electromagnetic noise radiated from the electronic equipment (hereinafter referred to simply as “noise”) and resistance (immunity) to external noise entering from the outside. : Electro Magnetic Compatibility), and it is even more important to design and analyze equipment with high EMC performance.

  As one of such EMC performance evaluation methods, noise that has entered from an external object to an evaluation object such as a printed circuit board constituting an electronic device or an electronic component (such as an LSI) mounted on the evaluation object is generated. There is known a method of visualizing a noise propagation path indicating how noise propagates in an evaluation object and evaluating the EMC performance of the evaluation object based on the visualization.

  And as a specific method for easily visualizing noise, by applying noise to the wire harness connected to the evaluation object using an injection probe, the noise is injected into the evaluation object, At this time, a method has been proposed in which noise generated from an evaluation object is detected by a noise visualization antenna and the result is displayed as a noise intensity distribution diagram (see, for example, Patent Document 1).

  That is, in this method, noise is spatially applied to the wire harness of the evaluation object (referred to as “test object” in Patent Document 1) by a so-called BCI (Bulk Current Injection) method. On the other hand, the noise visualization antenna provided so as to face the detection area (scan area) in the evaluation object is composed of a plurality of minute antenna elements provided over the entire scan area, and is evaluated by each of these minute antennas. Noise from the object is detected. Then, a noise intensity distribution diagram is generated based on the detection result by each minute antenna.

  However, in the noise visualization method described in Patent Document 1, since the noise visualization antenna is formed by arranging a plurality of minute antennas in the scan area in advance, the noise visualization antenna as a whole is an evaluation object. Cannot be close enough. Moreover, in order to increase the detection system (resolution), it is preferable to detect noise at a pitch as short as possible. However, in the case of a configuration in which a plurality of minute antennas are arranged in advance, the detection pitch (that is, between adjacent minute antennas) is detected. There is a limit to reducing the interval), and it is difficult to make the pitch sufficiently short.

  Therefore, the spatial resolution of the noise propagation path / intensity is lowered, and the noise propagation path / intensity may be unclear. In addition, the evaluation result (visualization result) becomes uneven due to the strength of detection sensitivity caused by the arrangement interval of the minute antennas. Moreover, since the application of noise to the evaluation object is performed spatially (by electromagnetic coupling) using the injection probe, a part of the noise from the injection probe may be mixed into the noise visualization antenna. The accuracy of the detection result may be lowered.

  On the other hand, a method has been proposed in which noise is detected while scanning a minute antenna probe along a two-dimensional plane of a printed circuit board to be measured, and a noise intensity distribution map is generated based on the detection result (for example, (See Patent Document 2).

JP 2001-124808 A JP 2000-19204 A

  The noise visualization method according to Patent Document 2 scans a minute antenna probe and can detect noise at a short pitch. Therefore, even in the noise visualization method of Patent Document 1, if the method of detecting noise while scanning the minute antenna probe as in the method of Patent Document 2 is employed, the spatial resolution is lowered and the evaluation result is uneven. Such a problem is solved to some extent.

  However, in the noise visualization method of Patent Document 1, even if a method of detecting noise while scanning the minute antenna probe is adopted, noise from the injection probe is mixed into the minute antenna probe and the accuracy of the detection result is lowered. This problem (decrease in detection accuracy) becomes more prominent as the minute antenna probe is closer to the injection probe.

  In addition, the method of Patent Document 2 does not inject noise from the outside and visualize the propagation path / intensity, but simply detects noise radiated during operation of the printed circuit board to be measured and calculates its intensity distribution. It is to be visualized. Therefore, the measurement result can be obtained by scanning the minute antenna probe once on the two-dimensional plane.

  However, in the method of injecting noise from the outside to the evaluation object and visualizing the propagation path / intensity as in the noise visualization method of Patent Document 1, in general, noise of plural kinds of frequencies is injected for each frequency. It is desirable to evaluate the noise intensity distribution. In such a case, simply adopting the method of detecting noise while scanning the micro antenna probe as in Patent Document 2, the more the frequency of noise to be injected, the more the evaluation time increases. End up.

  That is, if there is only one type of noise frequency to be evaluated (injected), the noise intensity distribution can be visualized and evaluated by scanning the micro antenna probe once while injecting noise of that frequency. it can. However, if there are a plurality of noise frequencies to be evaluated, it is necessary to scan the minute antenna probe by the number of times corresponding to the type of the frequency.

  Normally, the operation of detection → movement → detection → movement → detection ... is repeated during one scan, and the movement pitch is set as short as possible in order to improve the detection accuracy (that is, detection). Since a large number of points are set), it takes a relatively long time (for example, half day to one day) just to obtain an evaluation result for noise of one frequency for the entire evaluation object. Therefore, as the frequency of noise to be injected increases, the number of times the micro antenna probe is scanned increases accordingly, and the time for obtaining the evaluation results of all frequencies becomes enormous.

  The present invention has been made in view of the above problems, and in evaluating a noise propagation path in an evaluation object when noise is injected from the outside into the evaluation object, an evaluation result having a high spatial resolution is obtained as a result of the noise to be injected. It is an object of the present invention to obtain a signal with high accuracy in a short time regardless of the type of frequency.

  The noise evaluation method according to claim 1, which has been made to solve the above problem, generates a high-frequency signal having a predetermined frequency, and directly applies the high-frequency signal to a predetermined application site in the evaluation object. Noise detecting means for detecting noise generated from the evaluation object is sequentially moved to a plurality of predetermined measurement points on the evaluation object. For each of the measurement points, the frequency of the noise to be measured is sequentially set to one or more predetermined measurement frequencies, and the frequency of the high frequency signal is set to be synchronized with the measurement frequency. The intensity of noise detected by the noise detection means is measured for each measurement frequency. And the evaluation result in which the measured intensity | strength and the measurement point were matched is output.

  That is, in the present invention (Claim 1), the generated high-frequency signal is not applied spatially (by electromagnetic coupling) to the evaluation object as in the BCI method in Patent Document 1 described above, but instead of the evaluation object. Apply directly to the application site. For this reason, it is possible to prevent the occurrence of a problem that a part of the high-frequency signal to be applied to the evaluation object interferes with the noise detection means and the detection accuracy of the noise detection means decreases, which has been a problem in the BCI method. it can.

  In addition, detection of noise generated from the evaluation object is performed while sequentially moving the noise detection means to a plurality of measurement points. Therefore, it is possible to detect noise and measure intensity with high spatial resolution by appropriately setting measurement points.

  Moreover, for each measurement point, the frequency to be measured is sequentially set to one or a plurality of predetermined measurement frequencies, and the high-frequency signal is synchronized with the set measurement frequency (that is, the same frequency). Also set the frequency. That is, at one measurement point, the frequency of the frequency to be measured is swept to the one or more measurement frequencies while being synchronized with the frequency of the high frequency signal, and the noise intensity at each measurement frequency is measured, and the next measurement point is measured. Move to. This is performed for each of a plurality of measurement points.

  Therefore, even if there are multiple types of high frequency signals to be applied to the evaluation object, the number of times that the noise detection means is sequentially moved (scanned) to the plurality of measurement points is only one, and the frequency types are changed as in the past. There is no need to scan for the corresponding number of times.

  Therefore, according to the noise evaluation method of the first aspect, in evaluating the noise propagation path in the evaluation object when noise (high-frequency signal) is applied from the outside to the evaluation object, an evaluation result with high spatial resolution is obtained. Regardless of the type of frequency (frequency to be measured) of the applied high frequency signal, it can be obtained in a short time and with high accuracy.

  Next, the invention described in claim 2 is a high-frequency signal generating unit that generates a high-frequency signal having a predetermined frequency and applies the high-frequency signal to the evaluation object, a noise detection unit that detects noise generated from the evaluation object, and the noise. A moving means for sequentially moving the detection means to a plurality of predetermined measurement points in the evaluation object, a measurement means for measuring the intensity of noise detected by the noise detection means for each measurement point, and the measurement means An evaluation result output unit that outputs an evaluation result in which a measured intensity and a measurement point are associated with each other.

  Then, for each measurement point, the measurement frequency setting means for sequentially setting the frequency to be measured in the measurement means to one or more predetermined measurement frequencies, and the frequency of the high frequency signal generated by the high frequency signal generation means are measured. High-frequency signal frequency setting means for setting so as to synchronize with the measurement frequency set by the frequency setting means.

Further, the high-frequency signal generating means is connected to a predetermined application site to which the high-frequency signal is applied in the evaluation object so that the high-frequency signal is directly applied to the application site.
Therefore, according to the noise evaluation system according to claim 2 configured as described above, the noise evaluation method according to claim 1 can be realized, and the same effect as in claim 1 can be obtained.

  Here, it is possible to appropriately set which part to apply the high frequency signal to the evaluation object, that is, which part is the application part. For example, as described in claim 3, When the evaluation object has a configuration including an interface unit that is electrically connected to the outside when the evaluation object is operated, the interface unit may be an application site. As described, when the evaluation target is a printed circuit board on which a predetermined wiring pattern is formed, a predetermined part in the wiring pattern may be set as the application part.

  In the former case (Claim 3), a high frequency signal is applied to the interface unit, and it is possible to evaluate how the applied high frequency signal propagates in the evaluation object. Therefore, it is possible to appropriately evaluate the resistance against external noise input from the outside via the interface unit.

  In the latter case (Claim 4), it is possible to evaluate how a high-frequency signal applied to a predetermined part in the wiring pattern propagates on the printed circuit board. Therefore, when a circuit is actually formed on the wiring pattern, the propagation performance of the noise generated in the evaluation object, such as how the noise generated from the circuit elements constituting the circuit propagates on the printed circuit board Can be appropriately evaluated.

  Further, in the case where the predetermined part in the wiring pattern is used as the application part, it may be configured as in claim 5. That is, the invention according to claim 5 is the noise evaluation system according to claim 4, wherein the high-frequency signal from the high-frequency signal generating means is a balanced mode signal, and the high-frequency signal from the high-frequency signal generating means is not used. Balance-unbalance conversion means for converting the signal into a balanced mode signal is provided. Then, the high frequency signal from the high frequency signal generating means is applied to the application site after being converted into the unbalanced mode by the balanced / unbalanced converting means.

  That is, when the application target of the high frequency signal is a wiring pattern on a printed circuit board, the application target mode is generally an unbalanced mode. On the other hand, when the applied high-frequency signal is a balanced mode signal, if it is applied to the application site as it is, various problems such as power loss due to mismatch between balanced and unbalanced modes occur as is well known.

  Therefore, if the high-frequency signal in the balanced mode is converted to the unbalanced mode and applied to the application site of the wiring pattern, the high-frequency signal in the same mode is applied when the application site is in the unbalanced mode. Therefore, it is more preferable.

  By the way, noises generated from the inside of specific parts (for example, semiconductor integrated circuits) constituting a circuit have become particularly problematic in various circuits formed on a printed circuit board in recent years. Usually, when evaluating how noise generated by a semiconductor integrated circuit propagates on a printed circuit board, it is necessary to evaluate the semiconductor integrated circuit mounted on the printed circuit board and operating. However, with such an evaluation method, it is difficult to separately evaluate the performance of the semiconductor integrated circuit and the performance of the printed circuit board.

  Therefore, for example, as described in claim 6, the printed circuit board is configured to mount a semiconductor integrated circuit having a plurality of terminals, and a terminal connection portion to which the plurality of terminals are connected as a wiring pattern Is formed, the high frequency signal may be applied using the terminal connection portion as an application site.

  In this way, if a high frequency signal is applied to the terminal connection portion of the semiconductor integrated circuit on the printed circuit board, the noise generated from the semiconductor integrated circuit is simulated by the high frequency signal, and how the high frequency signal is transmitted on the printed circuit board. It is possible to evaluate whether or not to propagate. Therefore, it is possible to evaluate the performance of the printed circuit board alone with respect to noise generated from the semiconductor integrated circuit by separating the semiconductor integrated circuit.

  Next, a seventh aspect of the present invention is the noise evaluation system according to any one of the second to sixth aspects, wherein the high-frequency signal is provided between the high-frequency signal generating means and the application site. DC bias adding means for applying a predetermined DC bias is provided.

  According to the noise evaluation system according to claim 7 configured as described above, since the high-frequency signal to which the DC bias is applied can be applied to the evaluation object, the evaluation object is actually operating. When the voltage at the application site is a predetermined voltage other than 0V (for example, a power supply line to which a DC power supply is input), a high-frequency signal is applied to the DC bias while adding a DC bias of the voltage to the application site. Can be superimposed. Therefore, it is possible to reproduce the state in which noise is superimposed on the voltage input to the application site during steady state, and the noise propagation path can be evaluated under the same conditions as the actual operating state. The result can be obtained.

  Next, the invention according to claim 8 is the noise evaluation system according to any one of claims 2 to 7, wherein the system is provided between the high-frequency signal generating means and the application site, and the high-frequency signal is provided. Of the high-frequency signal output from the output circuit, an input amount measuring means for measuring the input amount actually input from the application site into the evaluation object is provided.

  How much the high-frequency signal output from the high-frequency signal generator is actually input to the evaluation object depends on the impedance in the evaluation object viewed from the application site, the impedance of the transmission system through which the high-frequency signal is transmitted, and the like. . Moreover, each of these impedances has a frequency characteristic and varies depending on the frequency. Therefore, the input amount of the high-frequency signal that is actually input to the evaluation object varies depending on the frequency of the applied high-frequency signal.

  Therefore, as described in claim 8, if the input amount actually input to the evaluation object is measured, the intensity measured by the measuring means can be evaluated in association with the input amount. For example, It is also possible to normalize the intensity measured for each frequency by the input amount, and it becomes possible to more appropriately perform relative evaluation of the noise intensity for each frequency.

  Next, a ninth aspect of the invention is the noise evaluation system according to any one of the second to eighth aspects, wherein the spectrum analyzer functions as a measurement unit and the tracking functions as a high-frequency signal generation unit. The tracking generator is built in the spectrum analyzer together with the high-frequency signal frequency setting means.

  That is, the intensity of noise detected by the noise detection means is measured using a spectrum analyzer with a built-in tracking generator. A tracking generator built in a spectrum analyzer generally generates a high-frequency signal having a frequency that is synchronized with (same as) a frequency to be measured in the spectrum analyzer.

  Therefore, if a spectrum analyzer with a built-in tracking generator is used in this way, the noise evaluation system of the present invention can be configured more simply and evaluation can be performed efficiently.

  Next, the invention according to claim 10 is the noise evaluation system according to any one of claims 2 to 9, wherein the evaluation result output means outputs the evaluation result to the intensity distribution for each measurement point. Is output in a state that is visually recognizable.

  According to the noise evaluation system according to claim 10 configured as described above, an evaluation result in which the noise intensity distribution for each measurement point is visualized can be obtained. Therefore, the noise intensity distribution in the evaluation object can be visually determined. It can be easily grasped.

It is a block diagram showing schematic structure of the noise evaluation system of 1st Embodiment. It is a flowchart showing the noise propagation visualization control process which PC performs. It is a figure showing a noise intensity distribution figure, (a) is a noise intensity distribution figure at the time of applying the noise visualization method of this invention, (b) is a noise intensity distribution figure at the time of applying the conventional noise visualization method. . It is a block diagram showing schematic structure of the noise evaluation system of 2nd Embodiment. It is a block diagram showing schematic structure of the noise evaluation system of 3rd Embodiment.

Preferred embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 shows a schematic configuration of the noise evaluation system of the present embodiment. As shown in FIG. 1, the noise evaluation system 1 of the present embodiment is configured for the purpose of visualizing the propagation path of external noise and evaluating the noise resistance performance based on this, and is mainly evaluated. An object 11, a signal generator (SG) 12 that generates a noise signal (high frequency signal) to be applied to the evaluation object 11, a probe 17 that detects noise generated from the evaluation object 11, and a detection by this probe 17 The spectrum analyzer 21 that measures the noise intensity based on the detected signal, the support 18 that supports the probe 17, and the probe 17 is moved to a predetermined measurement point on the evaluation object 11 by moving the support 18. And a position controller 2 that outputs a drive signal for driving the drive mechanism 19. The position of the probe 17 is controlled via the position controller 20 and the spectrum analyzer 21 and the signal generator 12 are controlled. Based on the measurement data input from the spectrum analyzer 21, the noise propagation path evaluation result (noise intensity) And a personal computer (PC) 23 that displays and outputs a distribution map.

  The evaluation object 11 is, for example, an electronic device (printed circuit board) in which a circuit having a specific function is formed by mounting various electronic components on a printed board on which a predetermined wiring pattern is formed. A connector 16 is provided at the end. The connector 16 has a power supply terminal for supplying power to the electronic device and a signal input / output terminal for inputting / outputting various signals between the electronic device and external devices / circuits. Yes. That is, the evaluation object 11 is configured to receive power supply and input / output signals through the connector 16 when actually operating.

  In the present embodiment, a noise signal from the signal generator 12 is applied to the evaluation object 11, and this noise signal is also applied to one or a plurality of predetermined terminals in the connector 16. The

In addition, the evaluation object 11 is fixed on the installation table 26 via spacers 27 and 28.
The signal generator 12 generates a noise signal according to the SG control signal from the PC 23. The SG control signal from the PC 23 indicates the frequency of the noise signal to be generated. Therefore, the signal generator generates a noise signal having a frequency indicated by the SG control signal.

  The noise signal generated by the signal generator 12 is at a relatively weak level. Therefore, in the present embodiment, the noise signal output from the signal generator 12 is amplified by the amplifier (Amp) 13 at a predetermined amplification factor.

Further, a directional coupler 14 and a bias tee 15 are connected on the transmission path from the amplifier 13 to the connector 16 of the evaluation object 11.
The directional coupler 14 is provided to measure the amount of noise signal output from the signal generator 12 and actually input into the evaluation object 11 via the connector 16. A power measuring device 32 for measuring the power and a power measuring device 33 for measuring the reflected wave power are connected to each other. Based on the measurement results of the power measuring devices 32 and 33, the input amount of the noise signal actually input into the evaluation object 11 can be grasped quantitatively. Note that each of the power measuring instruments 32 and 33 in the present embodiment is configured by a power sensor and a power meter.

  The bias tee 15 includes a direct-current bias generator (DC) 31 that generates a direct-current bias having a predetermined voltage value. The direct-current bias from the direct-current bias generator 31 is superimposed on the noise signal transmission path via the coil L1. The Further, the noise signal transmitted from the signal generator 12 via the amplifier 13 and the directional coupler 14 is output to the connector 16 side, and the DC bias from the DC bias generator 31 does not flow into the directional coupler 14 side. For this purpose, a coupling capacitor C1 is provided.

  The bias tee 15 superimposes the noise signal from the signal generator 12 and the DC bias from the DC bias generator 31, and the noise signal including the DC bias (in other words, the DC voltage on which the noise signal is superimposed) is evaluated. 11 is applied to the connector 16.

  A noise signal including a direct current bias output from the bias tee 15 is applied to a power supply terminal to which power is supplied in the connector 16 when the evaluation object 11 actually operates, for example. Therefore, the DC bias generation unit 31 generates a DC bias having the same voltage as the power supply voltage input to the power supply terminal when the evaluation object 11 normally operates. As described above, by applying the same DC bias as the power supply voltage applied during the actual operation together with the noise signal, it is possible to reproduce a state in which the noise signal is mixed from the power supply terminal during the actual operation.

  Note that it is not essential to superimpose a DC bias using the bias tee 15 as described above, and any terminal (for example, a ground terminal or a signal input / output terminal) to which a DC voltage is not constantly applied during actual operation. DC bias is not necessary. Further, even if the application part of the noise signal is a part where a DC voltage is applied during normal operation, such as a power supply terminal, for example, it is not always necessary to superimpose a DC bias, and only the noise signal is applied. You may do it.

  In the case where only the noise signal is applied without superimposing the DC bias, the bias tee 15 may be removed as it is, or only the coupling capacitor C1 may be connected.

  Thus, in the noise evaluation system 1 of the present embodiment, the noise signal is not applied spatially (by electromagnetic coupling) to the evaluation object 11 as in the BCI method in Patent Document 1 described above. The signal is directly transmitted by wire via the directional coupler 14 and the bias tee 15 and directly applied to the connector 16.

  Next, the probe 17 is constituted by, for example, a minute loop antenna for detecting noise generated from the evaluation object 11. There are a variety of specific configurations of the probe 17. For example, when only an electric field can be measured as noise, an electric field measurement probe may be used. When only a magnetic field can be measured as noise, the probe 17 is used for magnetic field measurement. A probe may be used, and if both electric and magnetic fields need to be measured, a probe capable of measuring both of them may be used. Specifically, the configuration and performance of the probe are evaluated. What is necessary is just to determine suitably according to the objective.

A detection signal indicating noise detected by the probe 17 is input to the spectrum analyzer 21 via the signal cable 22.
The probe 17 is supported by a support portion 18 and is configured to be movable together with the support portion 18 by a movable table 10 including the support portion 18 and a driving mechanism 19 that drives the support portion 18. .

  Specifically, as shown in the one-dot chain line in FIG. 1, it can move in a predetermined measurement area on the evaluation object 11 in the X direction, the Y direction, and the Z direction, respectively, and in the θ direction. It is also possible to rotate. That is, the movable table 10 of this embodiment is configured as an XYZθ type stage. The X direction and the Y direction are parallel to the evaluation object 11 (that is, parallel to the plate surface of the printed circuit board constituting the evaluation object 11), and the Z direction is perpendicular to the evaluation object 11 ( That is, it is perpendicular to the plate surface of the printed circuit board constituting the evaluation object 11.

  When the movable table 10 moves the probe 17 in the X, Y, Z, and θ directions, the position controller 20 outputs a drive signal to the drive mechanism 19 based on a position (X, Y, X, θ) control signal from the PC 23. Is done.

  On the other hand, the position (measurement point) at which noise detection by the probe 17 is performed on the evaluation object 11 is performed in advance within a predetermined measurement range on a two-dimensional plane (XY plane) parallel to the evaluation object 11. Points are set. Specifically, measurement points of n columns at equal intervals in the X direction and m rows at equal intervals in the Y direction are preset in the measurement range. Of course, the number, interval, and position of the measurement points can be determined as appropriate.

Therefore, when noise detection by the probe 17 is performed, the probe 17 is sequentially moved to the plurality of measurement points.
Note that the movable table 10 of the present embodiment is a contact-sensitive moving mechanism for movement in the Z direction (specifically, the downward direction toward the evaluation object 11). That is, every time the measurement point is moved, the probe 17 is moved downward at the measurement point until the probe 17 comes into contact with the evaluation object 11. When it is detected that the probe 17 has come into contact with the evaluation object 11, the downward movement is stopped there, and the movement is stopped upward by a predetermined distance (a minute distance) from the stop position. To do. As described above, since the movement in the vertical direction is a contact sensing type, the probe 17 can be made to approach the evaluation object 11 as much as possible in the Z direction for each measurement point, and highly sensitive noise detection is possible. It has become.

  In the present embodiment, the probe 17 is configured to move (rotate) not only in the X, Y, and Z directions but also in the θ direction. This is because the probe 17 has directivity. Therefore, noise is detected by changing the position (angle) in the θ direction at one measurement point, and the noise intensity for each θ is acquired, for example, the highest level data is set as the noise intensity at the measurement point. By performing appropriate data processing, highly accurate measurement results can be obtained at each measurement point.

  The spectrum analyzer 21 is a well-known measuring instrument that can measure the frequency characteristics of noise detected by the probe 17. In this embodiment, the operation of the spectrum analyzer 21 is controlled based on a spectrum control signal from the PC 23. Specifically, since data indicating the frequency to be measured is input as the spectrum analyzer control signal from the PC 23, the spectrum analyzer 21 determines the intensity of the set frequency component in the detected noise according to the data. taking measurement. Then, the measurement data (noise intensity) is output to the PC 23 together with the set frequency data.

  The PC 23 performs various processes necessary for evaluating the noise immunity performance of the evaluation object 11, and mainly outputs the position control signal to the position controller 20, thereby sequentially applying the probe 17 to each measurement point. Control of movement, control of noise intensity measurement in spectrum analyzer 21 by outputting spectrum analyzer control signal to spectrum analyzer 21, noise signal generated by signal generator 12 by outputting SG control signal to signal generator 12 Frequency control and processing of measurement data input from the spectrum analyzer 21 (creation of a noise intensity distribution diagram, etc.) are performed.

  In the present embodiment, a plurality of types of frequencies of the noise signal to be applied to the evaluation object 11 are set in advance, and the PC 23 has the frequency measured by the spectrum analyzer 21 and the frequency of the noise signal generated by the signal generator 12. Synchronous control of both frequencies is performed so as to be the same. That is, when setting a measurement frequency as a spectrum analyzer control signal to the spectrum analyzer 21, the PC 23 generates a noise signal having the same frequency as the measurement frequency set in the spectrum analyzer 21 together with the setting of the measurement frequency. The SG control signal indicating that it should be output. That is, the measurement frequency by the spectrum analyzer 21 and the frequency of the noise signal by the signal generator 12 are synchronized.

  Further, the PC 23 sequentially sets (sweeps) the measurement frequency in the spectrum analyzer 21 to the plurality of types of measurement frequencies for each measurement point. Therefore, the frequency of the noise signal generated by the signal generator 12 is also swept in synchronization with the measurement frequency sweep in the spectrum analyzer 21.

  After the measurement data is obtained for all measurement frequencies at one measurement point, the PC 23 moves the probe 17 to the next measurement point. Similarly, at the measurement point after the movement, the measurement frequency in the spectrum analyzer 21 is swept in synchronization with the frequency of the noise signal in the signal generator 12 to obtain measurement data of noise intensity for each measurement frequency.

  That is, in this embodiment, instead of sequentially switching the measurement points with the measurement frequency fixed, all the measurement frequencies to be measured at each measurement point by sweeping the measurement frequency for each measurement point. After acquiring the measurement data, it moves to the next measurement point. Therefore, even if a plurality of types of measurement frequencies are set, the movement (scanning) of the probe 17 to each measurement point is required only once as a whole.

  Then, the PC 23 creates a noise intensity distribution diagram indicating the noise intensity for each measurement point based on the measurement data input from the spectrum analyzer 21 for each measurement point. That is, the PC 23 stores two-dimensional planar image data of the evaluation object 11 in advance. For this reason, the PC 23 superimposes an image of the evaluation object 11 on which a distribution diagram (for example, a diagram in which a difference in density or a color is classified according to the noise strength) indicating the noise strength at each measurement point is superimposed. Create a noise intensity distribution chart.

  The PC 23 visualizes the noise propagation path / intensity distribution in the evaluation object 11 by displaying the created noise intensity distribution diagram on a display (not shown) or printing it out on paper or the like (see FIG. 3). Details will be described later.)

  FIG. 2 shows a flowchart of the noise propagation visualization control process executed by the PC 23 when the noise tolerance performance evaluation is performed in the noise evaluation system 1 of the present embodiment. However, among the processes shown in FIG. 2, the process indicated by a broken line is a process performed by each device other than the PC 23.

  When starting the noise propagation visualization control processing, the PC 23 first outputs measurement initial setting data to the spectrum analyzer (sparener) 21 and the signal generator (SG) 12 in S110. Specifically, for the spectrum analyzer 21, various settings data necessary for measurement and measurement data output, including data for setting an initial value at the start of measurement among a plurality of types of measurement frequencies, are controlled by the spectrum analyzer. Output as a signal. For the signal generator 12, setting data indicating that a noise signal having the same frequency as the initial value of the measurement frequency set for the spectrum analyzer 21 should be generated is output as an SG control signal.

As a result, the spectrum analyzer 21 and the signal generator 12 perform various initial settings necessary for starting measurement (S115).
Then, the PC 23 outputs initial position setting data to the position controller 20 in subsequent S120. That is, data (data indicating X, Y, Z coordinates and θ) for setting an initial position at the start of measurement among a plurality of measurement points is output as a position control signal.

  Thereby, the position controller 20 drives the drive mechanism 19, and the probe 17 is moved to its initial position (first measurement point) (S125). At this time, the position of the probe 17 in the Z direction is as close to the evaluation target 11 as possible at the measurement point as described above.

  When various initial settings are completed in this way, the PC 23 instructs the spectrum analyzer 21 and the signal generator 12 to execute measurement from the measurement frequency initially set in S110 in subsequent S130. Thereby, the measurement at the measurement point by the spectrum analyzer 21 and the signal generator 12 is started (S135).

  Specifically, in the signal generator 12, a noise signal having the same frequency as the set measurement frequency is generated and output to the evaluation object 11. The spectrum analyzer 21 measures the intensity of the detection signal (noise) detected by the probe 17 at the measurement frequency, and transfers the measurement result to the PC 23 together with the measurement frequency.

  When the PC 23 receives and stores the measurement data from the spectrum analyzer 21 in S140, the PC 23 determines whether or not measurement has been completed for all measurement frequencies to be measured at the current measurement point in S150. If the measurement frequency to be measured still remains (S150: NO), the measurement frequency data indicating the frequency to be measured next is output to the spectrum analyzer 21 and the signal generator 12 in S160.

  Thereby, in the signal generator 12, the frequency of the noise signal to be generated is changed to the newly set measurement frequency (S135). Further, the spectrum analyzer 21 performs noise intensity measurement of the newly set measurement frequency, and the measurement result (measurement data) is transferred to the PC 23 together with the measurement frequency (S135). The output measurement data is received and stored by the PC 23 (S140).

  When measurement is completed for all measurement frequencies to be measured (S150: YES), in subsequent S170, it is determined whether measurement has been completed for all set θ (angles). In the present embodiment, for example, the measurement is performed by changing the position (angle) of the probe 17 in the θ direction in four steps of θ = 0 °, 45 °, 90 °, and 135 °. Therefore, if measurement has not been completed for all four θs (S170: NO), θ direction movement data indicating that the position in the θ direction should be moved (that is, rotated) is output to the position controller 20 in S180. Then, the position of the probe 17 in the θ direction is moved (rotated). Then, the process returns to S130 again, and measurement from the initially set measurement frequency is started.

That is, the processing of S130 to S160 is performed for each set θ (four types in this example), and noise intensity data for each measurement frequency is acquired for each θ.
When measurement is completed for all four types of θ (S170: YES), in subsequent S190, whether or not scanning of all measurement points is completed, that is, a plurality of set measurement points (n columns × m). Whether or not the noise intensity measurement has been completed in all of the rows.

  At this time, if the measurement of all the measurement points has not been completed yet (S190: NO), the movement data in the X, Y, and Z directions necessary for the movement to the next measurement point is transmitted to the position controller 20 in S200. To move the probe 17 to the next measurement point. Then, the process returns to S130 again, and measurement from the initially set measurement frequency is started.

  When the measurement of noise intensity is completed for all measurement points (S190: YES), a noise intensity distribution diagram is created and displayed on the display in S210. Note that printing may be performed on paper or the like as described above. Thus, by creating and displaying the noise intensity distribution map, it is visualized how the noise signal applied from the outside via the connector 16 propagates through the evaluation object 11.

  FIG. 3 shows an example of a noise intensity distribution diagram created by the PC 23. 3A is a noise intensity distribution diagram when the noise visualization method of the present invention is applied, that is, a noise intensity distribution diagram created by the PC 23 in the noise evaluation system 1 of the present embodiment, and FIG. FIG. 9 is a noise intensity distribution diagram when a conventional noise visualization method is applied, that is, a noise intensity distribution diagram created by the method described in Patent Document 1 described above.

  Further, the noise intensity distribution diagram of FIG. 3 uses an electronic device in which various circuit elements such as a microcomputer are arranged on a printed circuit board as the evaluation object 11, and a power supply terminal in a connector 16 of the electronic device. 3 shows a noise intensity distribution at a predetermined measurement frequency when a noise signal including a DC bias is injected (applied).

  As is clear from FIG. 3, the noise intensity distribution diagram (FIG. 3 (b)) according to the conventional noise visualization method has a configuration in which a plurality of noise visualization antennas are fixedly arranged in advance, so that measurement points can be set in detail. In addition, since the noise injection is based on the BCI method and the injection noise interferes with the noise visualization antenna, the spatial resolution is low and the propagation path of the injected noise is not clear.

  On the other hand, the noise intensity distribution diagram (FIG. 3A) by the noise visualization method of the present invention has a high spatial resolution and a clear noise propagation path. This is because in the present invention (this embodiment), a noise signal is directly applied to the evaluation object 11, and a plurality of measurement points (n columns × m rows) in which the probes 17 are set at a fine pitch. This is due to the fact that the measurement is performed while sequentially moving to.

  As described above, in the noise evaluation system 1 of the present embodiment, the noise signal generated by the signal generator 12 is spatially (by electromagnetic coupling) to the evaluation object 11 as in the BCI method in Patent Document 1 described above. Instead of applying the voltage, the voltage is directly applied to the connector 16 of the evaluation object 11 via the amplifier 13, the directional coupler 14, and the bias tee 15. Therefore, it is possible to prevent a problem that the noise signal output from the signal generator 12 leaks spatially and interferes with the noise detection probe 17.

  In addition, detection of noise generated from the evaluation object 11 is performed while sequentially moving the probe 17 to a plurality of measurement points. Therefore, it is possible to detect noise and measure intensity with high spatial resolution by setting the measurement points with a fine pitch.

  Moreover, in this embodiment, the PC 23 controls the spectrum analyzer 21 and the signal generator 12 to sweep the measurement frequency in the spectrum analyzer 21 and to synchronize the frequency of the noise signal generated by the signal generator 12 with the sweep frequency. I have to. Thereby, measurement data for all of a plurality of types of measurement frequencies can be obtained at one measurement point.

  Therefore, even if there are many measurement frequencies to be measured, the number of times the probe 17 is scanned over all measurement points is only one, and the probe is scanned for each measurement frequency as in the past (that is, the measurement frequency is The measurement time can be greatly shortened compared to the method in which the more times the probe is scanned, the more times the probe is scanned.

  Therefore, according to the noise evaluation system 1 of the present embodiment, in evaluating the noise propagation path in the evaluation object 11 when a noise signal is applied to the evaluation object 11 from the outside, a visualization result (noise intensity) with high spatial resolution is obtained. Distribution map) can be obtained and the noise intensity distribution and propagation path can be easily and reliably grasped visually.

  Moreover, the visualization result can be obtained in a short time and with high accuracy regardless of the type of the frequency of the noise signal to be applied (that is, the measurement frequency set by the spectrum analyzer 21).

  In the present embodiment, the application part of the noise signal to the evaluation object 11 is a predetermined terminal (for example, a power supply terminal) in the connector 16. In addition to applying a noise signal, a DC bias is also applied by a bias tee 15.

  Therefore, it is possible to reproduce the state in which the noise signal is mixed from the power supply terminal when the evaluation object 11 is supplied with power and actually operating. How it propagates can be visualized. In other words, since the noise propagation path can be evaluated under the same conditions as the actual operation state, a more accurate evaluation result can be obtained, and the resistance to external noise input via the connector 16 can be appropriately set. Can be evaluated.

  Furthermore, in this embodiment, the input amount of the noise signal actually input to the evaluation object 11 is quantitatively grasped by the directional coupler 14 and the power measuring devices 32 and 33. Therefore, the measured noise intensity can be evaluated in association with the above input amount, for example, the noise intensity for each measurement frequency can be normalized by the input amount, and the relative evaluation of the noise intensity for each measurement frequency can be further performed. It can also be done appropriately.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the signal generator corresponds to the high-frequency signal generation means of the present invention, the probe 17 corresponds to the noise detection means of the present invention, the spectrum analyzer 21 corresponds to the measurement means of the present invention, and the connector 16 corresponds to the present invention. The bias tee 15 corresponds to DC bias adding means of the present invention, and the PC 23 corresponds to evaluation result output means, measurement frequency setting means, and high frequency signal frequency setting means of the present invention.

  Further, the PC 23, the position controller 20, and the drive mechanism 19 constitute a moving means of the present invention, and the directional coupler 14 and the power measuring devices 32 and 33 constitute an input amount measuring means of the present invention.

[Second Embodiment]
Next, the noise evaluation system of 2nd Embodiment is demonstrated using FIG. FIG. 4 is a configuration diagram showing a schematic configuration of the noise evaluation system 40 of the present embodiment.

  As shown in FIG. 4, the noise evaluation system 40 of this embodiment is mainly different from the noise evaluation system 1 of the first embodiment shown in FIG. 1 in the following points. That is, a spectrum analyzer 41 having a tracking generator (TG) 42 built in as a spectrum analyzer is used, a noise signal applied to the evaluation object 11 is supplied from the tracking generator 42, and a DC bias is not superimposed on the noise signal. In addition, it is applied to a predetermined signal input / output terminal of the connector 16 through the coupling capacitor C1, except that the evaluation object 11 is evaluated by supplying a DC voltage from the DC bias generator 31 to the power supply terminal of the connector 16. For example, the object 11 is in an operating state.

  Since other configurations are basically the same as those of the noise evaluation system 1 of the first embodiment, the same components as those of the noise evaluation system 1 of the first embodiment are denoted by the same reference numerals and description thereof is omitted. .

The tracking generator 42 is a known signal generator that outputs a high-frequency signal (noise signal) synchronized with the measurement frequency set in the spectrum analyzer 41.
Therefore, the PC 43 does not need to output an SG control signal to the signal generator 12 like the PC 23 of the first embodiment.

  As a result, the noise propagation visualization control process executed by the PC 43 in this embodiment is basically the same as the noise propagation visualization control process of the first embodiment shown in FIG. 2, but among them, S110, S130, and S160. Each of these processes is performed only for the spectrum analyzer 41. In addition, regarding the processing by the spectrum analyzer and the signal generator shown in S115 and S135, the signal generator may be read as the tracking generator 42 in this embodiment.

  As described above, in the noise evaluation system 40 according to the present embodiment, the tracking analyzer 42 includes the tracking generator 42, and the tracking generator 42 generates and outputs a noise signal. Therefore, compared with the noise evaluation system 1 of the first embodiment in which the signal generator 12 and the spectrum analyzer 21 are used together, the entire noise evaluation system 40 can be configured more simply, and various evaluations such as noise propagation paths and intensities can be efficiently performed. Can be done automatically.

[Third Embodiment]
Next, the noise evaluation system of 3rd Embodiment is demonstrated using FIG. FIG. 5 is a configuration diagram showing a schematic configuration of the noise evaluation system 50 of the present embodiment.

  As shown in FIG. 5, the noise evaluation system 50 of the present embodiment is mainly different from the noise evaluation system 40 of the second embodiment shown in FIG. 4 in the following points. That is, the evaluation object 51 is a single printed circuit board on which various circuit elements including a microcomputer are not yet mounted, and a noise signal from the tracking generator 42 is evaluated as it is without using an amplifier or a directional coupler. The point to be applied to the object 51 and the application part of the noise signal are not the connector 16 but a predetermined part in the wiring pattern formed on the printed circuit board. The point to be applied after conversion.

  Since other configurations are basically the same as those of the noise evaluation system 40 of the second embodiment, the same components as those of the noise evaluation system 40 of the second embodiment are denoted by the same reference numerals and description thereof is omitted. .

  The application part of the noise signal in the evaluation object 51 is a part on which the microcomputer is mounted on the printed circuit board, and more specifically, a plurality of signal terminals (pins for external connection) included in the microcomputer in the wiring pattern on the printed circuit board. Is a signal terminal connection portion 53 to which any of the above is connected.

  The noise signal from the tracking generator 42 is in a balanced mode, while the application site is in an unbalanced mode. For this reason, the noise signal from the tracking generator 42 is converted into the unbalanced mode by the balun 52 and then applied to the printed circuit board as the evaluation object 51. Therefore, the output of the balun 52 is connected to the signal terminal connection portion 53 and the ground terminal connection portion 54 (ground potential) on the printed board.

Note that a DC voltage from the DC bias generator 31 is supplied to the power supply line in the wiring pattern on the printed circuit board via the connector 16.
As described above, in this embodiment, the noise signal from the tracking generator 42 is applied to a portion (signal terminal connection portion 53) of the printed circuit board to which the terminal of the microcomputer is connected. The reason for this is to evaluate how noise generated from the inside of the microcomputer propagates on the printed circuit board when a circuit is actually formed on the printed circuit board.

  As described above, in recent years, various types of circuits formed on a printed circuit board have been particularly problematic because of noise generated from the inside of a semiconductor integrated circuit such as a microcomputer. In general, when evaluating how noise generated by a microcomputer or the like propagates on a printed circuit board, it is necessary to perform evaluation while the microcomputer or the like is mounted on the printed circuit board and operated. However, with such an evaluation method, it is difficult to separately evaluate the performance of a microcomputer or the like and the performance of a printed circuit board.

  Therefore, in this embodiment, by applying a noise signal to the part where the microcomputer terminal is connected to a single printed circuit board, noise generated from inside the microcomputer can be generated from the connected part without actually mounting the microcomputer. The state of flowing out on the printed circuit board is reproduced, and how the noise propagates on the printed circuit board is measured and evaluated.

  Therefore, according to the noise evaluation system 50 of the present embodiment configured as described above, it is possible to evaluate how the noise signal applied to a predetermined part in the wiring pattern propagates on the printed circuit board.

  In particular, in the present embodiment, noise generated from the microcomputer is simulated by a noise signal from the tracking generator 42. Therefore, it is possible to evaluate how the noise generated from the microcomputer propagates on the printed circuit board without mounting the microcomputer. That is, the performance of a single printed circuit board with respect to noise generated from the microcomputer can be evaluated by separating the microcomputer without considering the performance of the microcomputer.

[Modification]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in each of the above embodiments, the probe 17 has been described as being movable in four directions of X, Y, Z, and θ. However, the probe 17 is not necessarily configured to be movable in all four directions. , Z movement only, or only X, Y movement.

  In the first and second embodiments, the noise signal is input to the evaluation object via the amplifier 13, the directional coupler 14, and the bias tee 15. Whether to provide the device 14 and the bias tee 15 can be determined as appropriate.

Moreover, the application part of the noise signal with respect to the evaluation object is not limited to the part exemplified in each of the above embodiments, and can be determined as appropriate.
In the third embodiment, the noise signal is converted into the unbalanced mode by the balun 52 and then applied to the evaluation object 11. However, the mode conversion is not necessarily performed, and the mode signal is not changed (it remains in the balanced mode). Even if it is applied, it can be measured.

  DESCRIPTION OF SYMBOLS 1,40,50 ... Noise evaluation system, 10 ... Movable table, 11,51 ... Evaluation object, 12 ... Signal generator, 13 ... Amplifier, 14 ... Directional coupler, 15 ... Bias tee, 16 ... Connector, 17 ... Probe 18, support unit 19 drive mechanism 20 position controller 21 41 spectrum analyzer 22 signal cable 23 PC 26 installation base 27 spacer 31 DC bias generator 32 , 33 ... Electric power meter, 42 ... Tracking generator, 52 ... Balun, 53 ... Signal terminal connection part, 54 ... Ground terminal connection part, C1 ... Coupling capacitor, L1 ... Coil

Claims (10)

While generating a high frequency signal of a predetermined frequency, the high frequency signal is directly applied to a predetermined application site in the evaluation object,
A noise detection means for detecting noise generated from the evaluation object is sequentially moved to a plurality of predetermined measurement points in the evaluation object,
For each measurement point, the frequency of the noise to be measured is sequentially set to one or a plurality of predetermined measurement frequencies, and the frequency of the high-frequency signal is set to be synchronized with the measurement frequency. Measure the intensity of noise detected by the noise detection means for each measured frequency,
An evaluation result in which the measured intensity is associated with the measurement point is output. High-frequency signal generating means for generating a high-frequency signal of a predetermined frequency and applying it to the evaluation object;
Noise detecting means for detecting noise generated from the evaluation object;
Moving means for sequentially moving the noise detection means to a plurality of predetermined measurement points in the evaluation object;
Measuring means for measuring the intensity of noise detected by the noise detecting means for each measurement point;
An evaluation result output means for outputting an evaluation result in which the intensity measured by the measurement means is associated with the measurement point;
A noise evaluation system comprising:
For each measurement point, measurement frequency setting means for sequentially setting the frequency to be measured in the measurement means to one or a plurality of predetermined measurement frequencies;
High-frequency signal frequency setting means for setting the frequency of the high-frequency signal generated by the high-frequency signal generating means to be synchronized with the measurement frequency set by the measurement frequency setting means;
With
The high-frequency signal generating means is connected to a predetermined application site to which the high-frequency signal is applied in the evaluation object so that the high-frequency signal is directly applied to the application site. system. The noise evaluation system according to claim 2,
The evaluation object includes an interface unit that is electrically connected to the outside when the evaluation object is operated.
The noise application system, wherein the application site is the interface unit. The noise evaluation system according to claim 2,
The evaluation object is a printed circuit board on which a predetermined wiring pattern is formed,
The application site is a predetermined site in the wiring pattern. A noise evaluation system, wherein: The noise evaluation system according to claim 4,
The high-frequency signal from the high-frequency signal generating means is a balanced mode signal,
Comprising balanced-unbalanced converting means for converting the high-frequency signal from the high-frequency signal generating means into a signal in an unbalanced mode;
The noise evaluation system, wherein the high-frequency signal from the high-frequency signal generating means is applied to the application site after being converted into an unbalanced mode by the balance-unbalance conversion means. The noise evaluation system according to claim 4 or 5,
The printed circuit board is configured so that a semiconductor integrated circuit having a plurality of terminals is mounted, and as the wiring pattern, a terminal connection portion to which the plurality of terminals are connected is formed,
The application part is the terminal connection part. A noise evaluation system, wherein: The noise evaluation system according to any one of claims 2 to 6,
A noise evaluation system, comprising: a DC bias adding unit that is provided between the high frequency signal generating unit and the application site and applies a predetermined DC bias to the high frequency signal. The noise evaluation system according to any one of claims 2 to 7,
Of the high-frequency signal provided between the high-frequency signal generating means and the application site and output from the high-frequency signal output circuit, the input amount actually input from the application site into the evaluation object is measured. A noise evaluation system comprising an input amount measuring means. The noise evaluation system according to any one of claims 2 to 8,
A spectrum analyzer that functions as the measuring means;
A tracking generator that functions as the high-frequency signal generating means;
With
The noise evaluation system, wherein the tracking generator is built in the spectrum analyzer together with the high frequency signal frequency setting means. The noise evaluation system according to any one of claims 2 to 9,
The evaluation result output means outputs the evaluation result in a state in which the intensity distribution for each measurement point is expressed so as to be visually recognizable.